Fuel pumps, for example those used in commercial aircraft, are often mounted on or in the fuel tank. If fitted in the fuel tank, each pump requires an aperture in the tank, which is a potential leakage point, for example, where high altitude differential pressures are present. Where multiple pumps are required, for example to increase flow rates or to enable fuel transfer between tanks, then multiple apertures are then needed. As well as an increased risk of leakage, each aperture produced increases costs and weakens the fuel tank.
The use of multiple pumps increases the desirability for ease of pump maintenance. A simple means for isolating the fuel tank and then withdrawing the pumps is needed. It is often difficult to remove the pumps for maintenance. Having a housing which allows complete dismantling of the wearable parts of the pump arrangement, from outside the fuel tank ameliorates the problem of maintenance, because it allows access from the outside of a fuel tank and there is no need to completely drain and purge the fuel tank for an engineer to access the fuel tank.